Thread: [GENERAL] upsert and update filtering

Hi



create table dimc1
(
col1 integer not null,
col2 char(10),
primary key (col1)
);



create table dimc2
(
col1 integer not null,
col2 char(10),
primary key (col1)
);

testdb=# select * from dimc1 order by 1;
 col1 |    col2
------+------------
  111 | foo111
  112 | foo112
(2 rows)

testdb=# select * from dimc2 order by 1;
 col1 |    col2
------+------------
  111 | foo111
  112 | foo122
  211 | foo211


In general it is my understanding it gows like this


insert into dimc1  select * from dimc2
on conflict (col1) do update
SET
col2 = EXCLUDED.col2
;


insert into dimc1  select * from dimc2
on conflict (col1) do update
SET
col2 = EXCLUDED.col2 returning *
;



So far so good

But what if in the conflict situation I want to performa the update ONLY if the record is different. The update seems
tohappen no matter what 
In other words is there anyway I can filter the update to happen (based on the sample date) only for 112 since col2 is
different?  



testdb=# select * from dimc1 order by 1;
 col1 |    col2
------+------------
  112 | foo112

testdb=# select * from dimc2 order by 1;
 col1 |    col2
------+------------
  112 | foo122




Thanks
Armand

armand pirvu <armand.pirvu@gmail.com> wrote:
>But what if in the conflict situation I want to performa the update ONLY if the record is different. The update seems
tohappen no matter what 
>In other words is there anyway I can filter the update to happen (based on the sample date) only for 112 since col2 is
different? 

That's quite possible. An ON CONFLICT's UPDATE accepts a WHERE clause,
which can reference both existing and excluded tuples. That WHERE clause
can back out of the UPDATE based on whatever criteria you like.

--
Peter Geoghegan

aaaa
That's because the access on this case is done to the existing row using the table's name / alias , and to the rows
thatwe attempt to insert using the excluded  

Thank you Peter


Armand

> On Jul 31, 2017, at 4:31 PM, Peter Geoghegan <pg@bowt.ie> wrote:
>
> armand pirvu <armand.pirvu@gmail.com> wrote:
>> But what if in the conflict situation I want to performa the update ONLY if the record is different. The update
seemsto happen no matter what 
>> In other words is there anyway I can filter the update to happen (based on the sample date) only for 112 since col2
isdifferent ? 
>
> That's quite possible. An ON CONFLICT's UPDATE accepts a WHERE clause,
> which can reference both existing and excluded tuples. That WHERE clause
> can back out of the UPDATE based on whatever criteria you like.
>
> --
> Peter Geoghegan